Template:When in sandbox
{{when in sandbox (|…) (|…)}} = {{#ifeq:{{SUBPAGENAME}}|sandbox |{{{1|/sandbox}}} |{{{2|}}}}}{{when in sandbox (|…) (|…)}} = {{when pagename is |/sandbox={{{1|/sandbox}}} |other={{{2|}}}}}
Returns "/sandbox" (or, if supplied, the parameter Template:Mono) if the template detects that the page where it is transcluded is a subpage named "sandbox" (i.e. is a sandbox page); otherwise it returns nothing (or, if supplied, Template:Mono). This can be useful to e.g. switch the version of a template used in its /doc[umentation] to the sandbox version (by using Template:Tcpl) when that documentation is transcluded on the template's sandbox page.